26
28
class _LRUNode(object):
27
29
"""This maintains the linked-list which is the lru internals."""
29
__slots__ = ('prev', 'next_key', 'key', 'value', 'cleanup', 'size')
31
__slots__ = ('prev', 'next_key', 'key', 'value')
31
def __init__(self, key, value, cleanup=None):
33
def __init__(self, key, value):
33
35
self.next_key = _null_key
36
self.cleanup = cleanup
37
# TODO: We could compute this 'on-the-fly' like we used to, and remove
38
# one pointer from this object, we just need to decide if it
39
# actually costs us much of anything in normal usage
42
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def __repr__(self):
43
40
if self.prev is None:
47
44
return '%s(%r n:%r p:%r)' % (self.__class__.__name__, self.key,
48
45
self.next_key, prev_key)
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def run_cleanup(self):
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if self.cleanup is not None:
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self.cleanup(self.key, self.value)
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# cleanup might raise an exception, but we want to make sure
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# to break refcycles, etc
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48
class LRUCache(object):
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49
"""A class which manages a cache of entries, removing unused ones."""
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def __init__(self, max_cache=100, after_cleanup_count=None,
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after_cleanup_size=symbol_versioning.DEPRECATED_PARAMETER):
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if symbol_versioning.deprecated_passed(after_cleanup_size):
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symbol_versioning.warn('LRUCache.__init__(after_cleanup_size) was'
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' deprecated in 1.11. Use'
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' after_cleanup_count instead.',
71
after_cleanup_count = after_cleanup_size
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def __init__(self, max_cache=100, after_cleanup_count=None):
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53
# The "HEAD" of the lru linked list
74
54
self._most_recently_used = None
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93
def __len__(self):
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94
return len(self._cache)
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"""Walk the LRU list, only meant to be used in tests."""
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node = self._most_recently_used
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if node.prev is not None:
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raise AssertionError('the _most_recently_used entry is not'
122
' supposed to have a previous entry'
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while node is not None:
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if node.next_key is _null_key:
126
if node is not self._least_recently_used:
127
raise AssertionError('only the last node should have'
128
' no next value: %s' % (node,))
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node_next = self._cache[node.next_key]
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if node_next.prev is not node:
133
raise AssertionError('inconsistency found, node.next.prev'
134
' != node: %s' % (node,))
135
if node.prev is None:
136
if node is not self._most_recently_used:
137
raise AssertionError('only the _most_recently_used should'
138
' not have a previous node: %s'
141
if node.prev.next_key != node.key:
142
raise AssertionError('inconsistency found, node.prev.next'
143
' != node: %s' % (node,))
96
@symbol_versioning.deprecated_method(
97
symbol_versioning.deprecated_in((2, 5, 0)))
147
98
def add(self, key, value, cleanup=None):
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"""Add a new value to the cache.
150
Also, if the entry is ever removed from the cache, call
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:param key: The key to store it under
154
:param value: The object to store
155
:param cleanup: None or a function taking (key, value) to indicate
156
'value' should be cleaned up.
99
if cleanup is not None:
100
raise ValueError("Per-node cleanup functions no longer supported")
101
return self.__setitem__(key, value)
103
def __setitem__(self, key, value):
104
"""Add a new value to the cache"""
158
105
if key is _null_key:
159
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raise ValueError('cannot use _null_key as a key')
160
107
if key in self._cache:
161
108
node = self._cache[key]
165
# Maintain the LRU properties, even if cleanup raises an
168
node.cleanup = cleanup
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self._record_access(node)
110
self._record_access(node)
171
node = _LRUNode(key, value, cleanup=cleanup)
112
node = _LRUNode(key, value)
172
113
self._cache[key] = node
173
114
self._record_access(node)
199
140
return self._cache.keys()
202
"""Get the key:value pairs as a dict."""
143
"""Get a new dict with the same key:value pairs as the cache"""
203
144
return dict((k, n.value) for k, n in self._cache.iteritems())
146
items = symbol_versioning.deprecated_method(
147
symbol_versioning.deprecated_in((2, 5, 0)))(as_dict)
205
149
def cleanup(self):
206
150
"""Clear the cache until it shrinks to the requested size.
212
156
while len(self._cache) > self._after_cleanup_count:
213
157
self._remove_lru()
215
def __setitem__(self, key, value):
216
"""Add a value to the cache, there will be no cleanup function."""
217
self.add(key, value, cleanup=None)
219
159
def _record_access(self, node):
220
160
"""Record that key was accessed."""
221
161
# Move 'node' to the front of the queue
249
189
# If we have removed all entries, remove the head pointer as well
250
190
if self._least_recently_used is None:
251
191
self._most_recently_used = None
255
# cleanup might raise an exception, but we want to make sure to
256
# maintain the linked list
257
if node.prev is not None:
258
node.prev.next_key = node.next_key
259
if node.next_key is not _null_key:
260
node_next = self._cache[node.next_key]
261
node_next.prev = node.prev
262
# And remove this node's pointers
264
node.next_key = _null_key
192
if node.prev is not None:
193
node.prev.next_key = node.next_key
194
if node.next_key is not _null_key:
195
node_next = self._cache[node.next_key]
196
node_next.prev = node.prev
197
# And remove this node's pointers
199
node.next_key = _null_key
266
201
def _remove_lru(self):
267
202
"""Remove one entry from the lru, and handle consequences.
324
259
self._update_max_size(max_size, after_cleanup_size=after_cleanup_size)
325
260
LRUCache.__init__(self, max_cache=max(int(max_size/512), 1))
327
def add(self, key, value, cleanup=None):
328
"""Add a new value to the cache.
330
Also, if the entry is ever removed from the cache, call
333
:param key: The key to store it under
334
:param value: The object to store
335
:param cleanup: None or a function taking (key, value) to indicate
336
'value' should be cleaned up.
262
def __setitem__(self, key, value):
263
"""Add a new value to the cache"""
338
264
if key is _null_key:
339
265
raise ValueError('cannot use _null_key as a key')
340
266
node = self._cache.get(key, None)
349
275
if node is not None:
350
276
# We won't be replacing the old node, so just remove it
351
277
self._remove_node(node)
352
if cleanup is not None:
356
node = _LRUNode(key, value, cleanup=cleanup)
280
node = _LRUNode(key, value)
357
281
self._cache[key] = node
359
self._value_size -= node.size
360
node.size = value_len
283
self._value_size -= self._compute_size(node.value)
361
284
self._value_size += value_len
362
285
self._record_access(node)
376
299
self._remove_lru()
378
301
def _remove_node(self, node):
379
self._value_size -= node.size
302
self._value_size -= self._compute_size(node.value)
380
303
LRUCache._remove_node(self, node)
382
305
def resize(self, max_size, after_cleanup_size=None):
added
removed
bzrlib/lru_cache.py
